[html] Best HTML5 markup for sidebar

First of all ASIDE is to be used only to denote related content to main content, not for a generic sidebar. Second, one aside for each sidebar only

You will have only one aside for each sidebar. Elements of a sidebar are divs or sections inside a aside.

I would go with Option 1: Aside with sections

<aside id="sidebar">
    <section id="widget_1"></section>
    <section id="widget_2"></section>
    <section id="widget_3"></section>
</aside>

Here is the spec https://developer.mozilla.org/en-US/docs/Web/HTML/Element/aside

Again use section only if they have a header or footer in them, otherwise use a plain div.